From Tetraquark to Hexaquark: A Systematic Study of Heavy Exotics in the Large $N_c$ Limit

Abstract

A systematic study of multiquark exotics with one or $N_c-1$ heavy quarks in the large $N_c$ limit is presented. By binding a chiral soliton to a heavy meson, either a normal $N_c$-quark baryon or an exotic $(N_c+2)$-quark baryon is obtained. By replacing the heavy quark with $N_c-1$ heavy antiquarks, exotic $(2N_c-2)$-quark and $2N_c$-quark mesons are obtained. When $N_c=3$, they are just the normal triquark baryon $Qqq$, the exotic pentaquark baryon $Q\bar{q}\bar{q}\bar{q}\bar{q}$, tetraquark di-meson $\bar{Q}\bar{Q}qq$ and the hexaquark di-baryon $\bar{Q}\bar{Q}\bar{q}\bar{q}barq\bar{q}$ respectively. Their stabilities and decays are also discussed. In particular, it is shown that the ``heavy to heavy'' semileptonic decays are described by the Isgur--Wise form factors of the normal baryons.

Comments: 14 pages in REVTeX, no Figures